because acute fear is a powerful instrument to divert attention away from more long term problems, and since the french president Hollande popularity is now at 17% he needs to show he can do something NOW to protect the population. ActionHero
Cheaper than starting a war and more result because France’s intervention in the Middle-East and Africa got him no bonus points especially after the latest run of terror attacks
So, FearUncertaintyDoubt and walk away as hero